Sheet-fed printing presses



March 11, 1969 P. J. OGDEN SHEET-FED PRINTING PRESSES Filed May 5, 1966 Sheet owmo 74 ommr 70 .rm5m5\ 75 6 FIG I 7 459M zzgwwfi' March 11,1969 P. .1. OGDEN SHEET-FED IRINTING PRES-5E5 Filed lay 5, 1966 Sheet FIGB March 11, 1969 P. J. OGDEN 3,431,844

SHEET-FED PRINTING PBESSES Filed May 5. 1966 v Sheet 3 of 4 H670 F|G.7b FIGS $1 FIGS March 11, 1969 P. J. OGDEN 3,431,344

SHEET-FED PRINTING PRESSES Filed ma 5, 1966 sneet of 4 United States Patent 19,053/65 US. Cl. 101234 4 Claims Int. Cl. B411 13/24, 5/16, 5/18 ABSTRACT OF THE DISCLOSURE A sheet-fed printing press has an electric control systern for controlling disabling of its printing means. The system includes a switch which is closed by manual operation of means for starting the feed of sheets to the press, a sensing device for sensing whether or not a sheet is properly positioned on its way to be printed, a pilot relay actuated by the sensing device, a disabling relay for disabling the printing means when it is deenergized and an auxiliary control relay. The latter relay energizes the disabling relay when it is itself energized. In a circuit for energization of the auxiliary control relay there are three contact arrangements in series. One contact arrangement is a contact pair which is closed and opened again at predetermined instants in the operating cycle of the printing press, this being in parallel with a holding contact pair which closes when the auxiliary control relay is energized. The second contact arrangement is a contact pair of the pilot relay which is normally closed but opens when no properly positioned sheet is sensed by the sensing device during a prescribed period in the operating cycle, and then closes again, the opening and closing taking place before and after the closing and opening of the first-mentioned contact pair. The third contact arrangement is the aforementioned switch in parallel with a normally open contact pair of the disabling relay.

This invention relates to sheet-fed printing presses (i.e. printing presses to which separate sheets, not continuous webs, are fed).

According to the invention, there is provided a combination of a sheet-fed printing press and an electric control system for controlling it, comprising printing means of the printing press, a sheet-sensing device associated with the press for sensing whether or not a sheet is correctly positioned at a particular location on its way to be printed by the printing means, a pilot relay connected for actuation by the sheet-sensing device, a disabling relay coupled to the printing means for disabling the printing means when it is deenergised, an auxiliary control relay arranged to energise the disabling relay when its own coil is energised and a circuit for energisation of the coil of the auxiliary control relay which comprises three contact arrangements in series, one of the contact arrangements being first and second contact pairs in parallel, the first contact pair being controlled so that it is closed and opened again at predetermined instants in the operating cycle ofthe printing press and the second contact pair being a holding contact pair which is closed when the coil of the auxiliary control relay is energised, another of the contact arrangements being a contact pair of the pilot relay which is normally closed but in the event of said sheet-sensing device not sensing a correctly positioned sheet during a prescribed period in the operating cycle of the printing press, said contact pair of the pilot relay is opened before said first contact pair-closes in that cycle andis closed again after said first contact pair opens in that cycle, the

3,431,844 Patented Mar. 11, 1969 "ice third contact arrangement being a normally open contact pair of said disabling relay in parallel with a switch which is closed by manual operation of means for starting feed of sheets to the press.

In one form of sheet-fed printing press with which the invention is concerned there are several printing mechanisms which should act in succession on each sheet, so as to apply ink successively to different areas of each sheet. It is desirable to provide means whereby in the event that a sheet is not presented to the sheet-feed mechanism when a sheet is due to be presented to it, or if a sheet is incorrectly presented to the sheet-feed mechanism, the several printing mechanisms are disabled in sequence in such manner that sheets which have already passed the sheet-feed mechanism are fully printed but each printing mechanism is disabled before the time at which a badly presented sheet or a sheet which is missing would have been printed thereby. It is also desirable to provide that an incorrectly presented sheet shall not be accepted by the sheet-feed mechanism and, as a refinement, that no further sheets will be accepted until the incorrectly presented sheet has been removed by hand.

Furthermore it is desirable that when, after correction of the fault, the first of the next series of sheets is correctly presented to the sheet-feed mechanism, the sheetfeed mechanism will automatically accept this and subsequent sheets without operation of any special control by the machine operator.

The apparatus which is described below with reference to the accompanying drawings has the desirable feature mentioned above.

The sheets presented to the sheet-feed mechanism are sensed at the appropriate times, when under normal circumstances they will be in the correct position for acceptance by the sheet-feed mechanism, by a sheet-sensing device which may, to give examples, be photoelectric,

ultrasonic or electromechanical. Such a sensing device is Y rendered effective periodically and works, in conjunction with an amplifier if necessary, to energise a pilot relay for a short period in the event of a sheet not being present or not being in its correct position. The pilot relay remains unenergised all the time sheets are properly presented. A suitable photoelectric sheet-sensing device includes two small lamps which are associated with lens systems which direct two narrow beams of light onto two places which are spaced apart in the direction perpendicular to the direction of feed of the sheets. When, and only when, a sheet is correctly presented to the sheetfeed mechanism, both beams of light will fall upon the leading edge of that sheet and the beams will be reflected by the paper towards respective photoelectric cells which are connected to an amplifier which feeds the pilot relay, the latter being energised when, and only when, light fails to fall on either or both of the photoelectric cells.

An example in accordance with the invention is described below with reference to the accompanying drawings, in which: I 4

FIGURE 1 is a circuit diagram of an electric control system for use with a printing press,

FIGURE 2 diagrammatically shows the printing mechanisms of the printing press and the arrangements for feeding sheets to them and taking sheets from them,

FIGURES 3 to 5 diagrammatically illustrate a printing mechanism of the printing press and an arrangement for disabling it,

FIGURE 6 shows a means for supplying ink or water for printing and an arrangement for disabling it,

FIGURES 7a and 7b show two different side views of a sheet-sensing device,

FIGURE 8 is a circuit diagram of the sheet-sensing device,

FIGURE 9 is a circuit diagram of an arrangement for controlling the speed of the press,

FIGURES 10 and 11 show a sheet-feed mechanism and an arrangement for disabling it, and

FIGURE 12 is a circuit diagram of an arrangement for starting the feed of sheets to the press.

In FIGURE 1 there are shown terminals 1 and 2 betwee which an alternating voltage is applied, the terminal 2 being earthed. All the contacts are shown in the positions which they occupy when the printing press is idle and no voltage is applied between the terminals 1 and 2. A coil 3 of an auxilliary control relay is connected to the terminal 2 and for energising this coil there is a circuit including three contact arrangements in series. One of these contact arrangements consists solely of a contact pair 4 of a pilot relay which is operated by an amplifier (not shown) in response to signals from a sheetsensing device (not shown). The sheet-sensing device could be, to give examples, photoelectric, ultrasonic or electromechanical and it is rendered effective periodically, when a sheet should be in a correct position for presentation to the sheet-fed mechanism, by a cam-controlled switch 18, which, when it is closed, either energises the sheet sensing device or renders the amplifier operative. In the former case the amplifier is continously operative and in the latter case, the sheet-sensing device is continously energised. Alternatively, the sheet-sensing device and the amplifier could be continuously operative and the switch 18 could be closed to permit and open to prevent transmission of signals from the amplifier to the coil of the pilot relay. The second contact arrangement consists of a contact pair of a cam-operated switch 5 in parallel with a holding contact pair 6 of the auxiliary control relay which has the coil 3. The third contact arrangement consists of normally open contact pairs 7 and 8, which are arranged in series, in parallel with a contact pair of a switch 11 which is automatically closed when a manually controlled handle or switch to start feeding sheets to the press is operated. The contact pairs 7 and 8 are provided on disabling relays which have coils 9 and 10, respectively, the arrangement being such that contact pairs 7 and 8 are closed when the relay coils 9 and 10 are energised.

A change-over contact 12. of the auxiliary control relay, the coil of which is shown at 3, is used to control the supply of power to relay coils 9 and 10 and also to control the supply of power to solenoid coils 13 and 14, of which the coil 13, when energised, operates a device which prevents the feed mechanism from accepting a badly presented sheet and of which the coil 14, when energised, releases this device to allow the feed mechanism to accept the first corectly presented sheet and subsequent correctly presented sheets after a fault has been cleared. Change-over contacts 15, i16 and 17 are some of the contacts of the disabling relays which have the coils 9 and 10, these contracts serving (in their upper positions) to disable the several printing mechanisms of the press or (in their lower positions) to render them operative, in accordance with whether or not the coils 9 and 10 are energised, i.e. in accordance with the position of the contact '12. The disabling of the printing mechanisms is effected not by the contacts 15, 16 and 17 alone but by them in cooperation with cam-operated switches which close i an appropriate sequence to operate the various disabling mechanisms at the correct time in the machine cycle.

Although only two disabling relays, with coils 9 and 10 and with contacts 7, 8, 15, 16 and 17 under their control, are shown in the accompanying drawing, obviously according to the requirements of the machine one or more further disabling relays, with additional contacts may be provided if necessary, the coil or coils of the further disabling relay or relays being under the control of the auxiliary control relay contact 12 generally as shown for the relay coils 9 and 10, and one normallyopen contact on each further disabling relay would be connected in series with contacts 7 and 8. Also, it is possible to have only one disabling relay, for example the one with the coil 9, in which case there will be in parallel with the switch 11 only one contact pair, i.e. a contact pair of one disabling relay and the necessary number of contacts 15, 16 etc. will all be the one disabling relay or on further relays controlled by the one disabling relay.

The function of the circuit above described and illustrated is as follows:

Initially, no voltage is applied between the terminals 1 and 2.

The positions shown in the drawing for the relay contacts are the positions which they take up under those conditions, these also being the positions they would take up to disable the printing mechanisms (thus the circuit has a fail safe :property). While the contact pairs 7 and '8 and the switch 11 are open and the contact pair 4 closed, switch 5 may be open or closed according to the position in which the machine has come to rest, and the holding contact pair in 6 is open. When a voltage is applied between terminals 1 and 2, a current is fed through contacts 12, .15, 16 and 1-7, in their upper positions, to disable the printing mechanisms and stop the sheet-feed mechanism while since the contact :pairs 7 and 8 and the switch 11 are open no current is fed to relay coil 3.

When all necessary preparations have been made, the press is started, and when the handle or switch provided to start the feeding of sheets to the press is operated, switch 11 is automatically closed without necessity of operating a separate special switch. Sheets are then taken from a pile and forwarded to the sheet-feed mechanism on the press, but there will be a delay of several revolutions of the printing cylinders before the first sheet reaches this sheet-feed mechanism, and during this delay the printing mechanisms must remain disabled. The switch 18 closes a circuit at the time in the cycle of operations when a sheet would normally be presented to the sheet-feed mechanism, and the sheet-sensing device becomes effective. If no sheet has yet arrived at the feed mechanism the sheet-sensing device and the amplifier operate so as to energise the pilot relay and open the pilot relay contact pair 4. After time has been allowed for the operation of the pilot relay, the camoperated switch 5 closes, but as contact pair 4- is open no current reaches the relay coil 3. Cam-operated switch 5 is then opened, and after a further delay the switch 18 is opened and the relay contact pair 4 closes once more as the sheet-sensing device is rendered ineffective. However, as the switch 5 and the contact pair 6 then remain open, relay coil 3 remains unenergised. This cycle of operations is repeated until the first sheet is correctly presented to the sheet-feed mechanism of the press, whereupon the switch 18 is closed at the appropriate time, and the sheetsensing device is rendered effective. In this case the relay contact pair 4 remains closed and when cam-operated switch 5 closes power is fed to relay coil 3 through relay contact pair 4, switch 5 and switch 11, so that relay coil 3 is energised and its holding contact pair 6 closes. Also, its contact 12 changes position so that disabling relay coils 9 and 10 are energised, and their contact pairs 7 and 8 close and their contacts 15, 16 and 17 are changed to their lower positions so that the printing mechanisms are rendered operative. Also the solenoid 13 is deenergised and the solenoid 14 is energised so that the feed mechanism is released for operation. Later in the cycle of operations, cam-operated switch 5 opens, but the power supply to relay coil 3 is maintained through its holding contact pair 6. Relay contact 4 remains closed when switch 18 is opened, and when the control provided to initiate feeding of sheets to the press is now released switch 11 opens but the power supply to relay coil 3 is maintained through relay contacts 7 and 8. The relay coil 3 is therefore maintained in an energised condition.

When the next correctly presented sheet arrives at the sheet-feed mechanism, and switch 18 is closed, relay contact 4 again remains closed, and the supply to the relay coil 3 is not broken, so that so long as sheets continue to be presented correctly, relay coils 3 will remain in a steady energised condition and, through contact 12 controlled by coil 3, relay coils 9 and are also maintained in a steady energised condition.

On the arrival of an incorrectly presented sheet or on the failure of a sheet to arrive when it should, the sheetsensing device detects the fault and when switch 18 is operate-d the pilot relay contact pair 4 opens and so relay coil 3 is deenergised. Its holding contact pair 6 opens and its contact 12 changes position and deenergises relay coils 9 and 10 so that relay contacts 7 and 8 also open and the contacts 15, 16 and 17 are changed to their upper positions so that the printing mechanisms are rendered inoperative in sequence. The solenoid '14 is deenergised and the solenoid 13 is energised so that the feed mechanism is stopped. The sheets which have already passed the sheet-feed mechanism are fully printed but each printing mechanism is disabled before the time at which the incorrectly presented sheet or the missing sheet would have been printed thereby. Later in the machine cycle switch 5 is closed, but the circuit supplying power to relay coil 3 is broken since relay contact 4 remains open and prevents energisation of the relay coil 3. Switch 5 then opens, and when later switch 18 opens and pilot relay contact 4 closes as the sheet-sensing device is rendered ineffective the circuit supplying power to relay coil 3 remains broken because the contact pairs 7 and 8 and the switch 11 are still open.

Now on further rotation of the press it sometimes happens that a sheet, the faulty position of which has just been detected, will correct its position as a result of the continuing movement of the sheet-forwarding tapes in the interval between initiation of the printing mechanisms being rendered inoperative and the actual stoppage of these tapes. It is desirable that this sheet shall not be accepted by the sheet-feed mechanism since this, upon the next scanning of the same sheet, would cause the printing mechanisms of the press to return to the printing positions but would not restart the sheet-separating and feeding device, so that on the next scanning there would be no sheet at the sheet-feed mechanism and the printing mechanisms would be disabled again. It is preferred in the trade to extract this sheet and possibly other sheets by hand since it is desirable to re-start in the normal man ner as already outlined above. The sheet cannot be accepted by the sheet-feed mechanism until the solenoid 14 is energised, which cannot occur until the coil 3 is energised and this coil cannot be energised until the switch 1.1 is operated through a deliberate manual action, which of course will not be taken until sheets have been removed as necessary.

The press will usually be allowed to continue to rotate with its printing mechanisms inoperative after detection of a badly presented sheet or detection that a sheet is missing, though its speed will normally be reduced to a minimum automatically through the action on the main drive motor control circuit of a contact or contacts on one or both of the disabling relays, the coils of which are shown in the drawing at 9 and 10, when these coils are deenergised. During the period when the press is running with its printing mechanisms inoperative and with no sheets being fed to it, the relay coil 3 will remain unenergised and will not switch the position of its contacts until the next correctly presented sheet arrives at the feed mechanism in the manner already described. Then, upon manual operation of the handle or switch which starts the sheet feed, the printing mechanisms will remain inoperative until the first sheet is presented correctly to the sheet-feed mechanism, when the printing mechanisms will be returned to the operative condition as already described and the press will resume full speed running either as a result of a manual operation or as a result of operation of a contact or contacts of one or both of the relays 9 and 10. The disabling relays could perform not only the functions indicated above but also the function of cutting out an electrically operated sheet-counter when a fault develops, so that only fully printed sheets are counted, and also the function of disabling, when a fault occurs, a device which sprays powder onto the printed sheets.

A major advantage of the arrangement according to the drawing is that in the event that the coil 3 of the auxiliary control relay fails or the supply to it be broken as the result of an electrical fault, the contact 12 will move to the uppermost or fault position and all the printing mechanisms will become inoperative and will remain so until the electrical fault is rectified.

Another important advantage is that in the event that one or both of the coils 9 and 10 of the disabling relays fails or the supply to them be broken as the result of an electrical fault, the contacts 7 or 8 respectively will open and break the supply to relay coil 3, whereupon contact 12 will change over to the fault position, ensure that neither of the coils 9 and 10 is energised and render inoperative all the printing mechanisms, which will remain inoperative until the electrical fault is rectified.

Another way of ensuring this protection is to arrange that the auxiliary relay coil 3 and the coils 9 and 10' and the coils of any further disabling relays that are provided are wired in series so that failure of any one coil automatically breaks the circuit to all coils.

Mechanical details of the printing press itself and further information concerning the electric control system for it are given below with reference to FIGURES 2 to 12 of the accompanying drawings. The description is brief and the figures are purely diagrammatic because the features concerned are, in the main, already well known.

Referring to FIGURE 2, which shows an offset litho graphic press, the numeral 20 represents the aforementioned sheet-separating and feeding device, which feeds sheets, one at a time, from a pile 21 down a slide 22 to the aforementioned sheet-feed mechanism, which is diagrammatically represented by the rectangle 19. This mechanism feeds the sheets between a rotary cylinder 24 and a feed device 23 which performs a reciprocatory rotary motion and consists of a quadrant mounted on an arm. Each sheet is accepted by the sheet-feed mechanism and fed between the feed device 23 and the cylinder 24 when, and only when, a barrier in the form of so-called front lays (not shown in FIGURE 2 has dropped away from the lower end of the slide 22 after being contacted by a properly positioned sheet. The sheet-sensing device is diagrammatically represented by the rectangle 25 and it senses whether or not a sheet is correctly positioned in contact with the front lays, ready to be accepted by the sheet-feed mechanism. After passing between the feed device 23 and the cylinder 24, each sheet passes between an impression cylinder 26 and a first blanket cylinder 27, which applies ink of one colour to selected areas of the paper, and then between the impression cylinder 26 and a second blanket cylinder 28, which applies ink of another colour to selected areas of the paper. Then the sheet passes round a delivery roller 29 and is transferred to a chain conveyor 30, which is only diagrammatically shown, from which it is delivered, by means not shown, to a pile 31 of printed sheets. Ink is transferred to the blanket cylinders 27 and 28 by plate cylinders 32 and 33, carrying the images which are to be transferred to the paper, and in contact with these cylinders are inking rollers 34 and 35 and damping rollers 36 and 37, which transfer ink and water to the plate cylinders.

The directions of rotation of some of the parts are indicated by arrows.

Disabling of the printing mechanisms is effected by moving the blanket cylinder 27 away from the impression cylinder 26 and the plate cylinder 32 and, shortly after that, moving the blanket cylinder 28 away from the impression cylinder 26 and the plate cylinder 33, and by 7 discontinuing the supply of ink and water to the rollers 34 and 36 and then the rollers 35 and 37.

The arrangement by which the blanket cylinder 27 is moved away is described below with reference to FIG- URES 3 to the corresponding arrangement for the blanket cylinder 28 is the same but this cylinder moves later.

FIGURE 3 shows by a full line 27A the printing position of the blanket cylinder 27 and by a broken line 278 its position when moved away, the axis of rotation of the cylinder when in the printing position being represented by a cross 47 and when in the other position by a cross 48. The cylinder has journals 27C coaxial with it and one of these turns in an offset bore in a bush 45 which is mounted in a support (not shown) in which it can turn about an axis 46 passing centrally through the bush. The bush is turned by a rod 49 which is pivotally connected at one end to a lug 44 which is fixed to the bush 45 and at the other end to a link 50 which is fixed to a shaft 51. The parts 27, 27C, 49 and 50 move from the positions indicated by full lines to the positions indicated by broken lines when the shaft 51 is turned clockwise by about a quarter turn. How this turning is effected is explained below with reference to FIGURES 4 and 5.

Fixed to the shaft 51 is an arm 52 on which are pivotally mounted two pawls 53 and 54 which are fixed relative to one another and carry a peg 61. Two arcuate catch plates 55 and 56 are mounted on the shaft 51 and free to turn about it. These catch plates carrying lugs 55A and 56A which are pivotally connected to links 57 and 58 at one end thereof, the other ends of these links being connected to a lever 59 which carries a cam follower 59A which engages a cam 60. When the cam 60 makes a half turn from its illustrated position, the links 57 and 58 move the catch plates 55 and 56 clockwise and anticlockwise, respectively about the shaft 51, closing the gap between them on the right-hand side of the shaft 51. In the illustrated position of the pawls 53 and 54, this movement of the catch plates causes the catch plate 55 to encounter the pawl 53 and turn the arm 52, and hence the shaft 51, clockwise, but the pawls 53 and 54 could instead occupy such positions that the catch plate 56 encounters the pawl 54 and turns the arm 52 and the shaft 51 anticlockwise. The positions of the pawls 53 and 54 are determined by the arrangement shown in FIGURE 5 which shows the peg 61 lying in a recess in a ring 62 which surrounds the shaft 51 and is free to turn about it under the action of rods 63A and 64A which are actuated by solenoids 63 and 64, of which the former is energized when the contact (or 16 or 17, FIGURE 1) is in its upper position and the latter is energised when the contact 15 (or 16 or 17) is in its lower position. FIGURE 5 shows the case where the solenoid 63 has been energised and this has re sulted in the ring 62 turning clockwise and the part of the ring defining one end of the recess striking the peg 61 and causing the arrangement of two pawls 53 and 54 to turn anticlockwise so that the pawl 53 can be engaged by the catch plate 55, and cause movement of the blanket cylinder 27 away from the impression cylinder 26 and the plate cylinder 32. If the solenoid 64 is now energised, the ring 62 will turn anticlockwise and the part of it defining the other end of the recess will strike the peg 61 and the pawls 53 and 54 will be turned so that the catchplate 56 will encounter the pawl 54 and this will cause the blanket cylinder 27 to move to its printing position.

How the arrangements for the supply of ink and water to the rollers 34 to 37 are disabled is described below with reference to FIGURE 6.

Each of the rollers 34 to 37 is supplied with ink or water by means of a respective system of rollers.

The reference 69 in FIGURE 6 denotes a roller of one of these roller systems. In normal operation, ink or water is transferred to the roller 69 by a roller 71 which is carried by an arm 72 and oscillates between a position of contact with the roller 69 and a position of contact with an ink-supply or water-supply roller '78. The arm 72 is fixed to a shaft 73 which is caused to turn in opposite directions by a cam 74 through the intermediary of a cam follower 74A, a lever 75, a link 76 and a further link 77 to which the shaft 73 is fixed, this link 77 having fixed to it a projection 80. When it is desired to stop the transfer of ink or water to the roller 69, the to and fro rotation of the shaft 73 is stopped by a catch 31 being brought into the path of movement of the projection 80 under the action of a solenoid 82 and against the action of a spring 84. The solenoid 82 is energised when the contact 15 (or 16 or 17) is in its upper position and when a contact pair of a microswitch 83 is closed, indicating that the projection 80 is in the illustrated position and that, therefore, the catch 81 can be swung into its path of movement.

The sheet-sensing device 25 of FIGURE 2 is diagrammatically shown in greater detail in FIGURES 7a, 7b and 8. There are two lamps 91 (only one of which is shown in FIGURE 7b) and narrow beams of light from them are directed by lenses 92 and prisms 93 toward two small areas 94 of the lower end of the slide 22 which are spaced apart in the direction transverse to the direction of movement of the sheets down the slide. If, and only if, these beams of light both strike a sheet of paper, indicating that a sheet is correctly positioned in contact with the front lays, light is reflected on to two photo-electric cells 95 (only one is shown in FIGURE 7a) and the coil 97 of the aforementioned pilot relay is energised through an amplifier96 when the switch 18 is closed. The contacts 98 of this pilot relay include the normally closed contact pair 4 shown in FIGURE 1.

To control the speed of the main motor which drives the printing cylinders etc., there is a pilot motor which operates to move the brush gear of the main motor. This pilot motor is in turn controlled by a speed up contactor having a coil 101 (FIGURE 9) which, when energised, causes the pilot motor to run in one direction and speed up the main motor and a slow down contactor having a coil 102 (FIGURE 9) which, when energised causes the pilot motor to run in the opposite direction and to slow down the main motor. When the pressure is running at a steady speed, neither of the coils is energised. The condition shown in FIGURE 9 is that where the press is not printing and is running at low speed. When the press is printing and sheets are being correctly presented to the sheet-feed mechanism, the positions of contacts .103 and 104, of one of the disabling relays which have coils 9 and 10, are changed and the position of contacts 108 are also changed. When a speed-up push button 105 is operated, by the person operating the press, the coil 101 is energised and so the main motor is speeded up until either the push button 105 is released or contacts 106 of a limit switch open, this limit switch being operated by the brush gear of the main motor when this has moved the maximum permissible amount in the speed up sense. The contacts 108 are contacts of another limit switch which is operated, to open the contacts 108, by the brush gear when this has moved the maximum desired amount in the slow down sense. If, when the press is printing, it is desired to slow it down manually, another push button 107 is pressed and so the coil 102 is energised and so the main motor is slowed down until either the push button is released or the contacts 108 are opened by the brush gear. When the sheet-sensing device senses that no sheet is properly presented to the sheet-feed mechanism and the disabling relays having coils 9 and 10 are accordingly deenergised, the contacts 103 and 104 move to the illustrated portions and the coil 102 is energised, to slow down the main motor, through the contacts 104 and 108 and a conductor .109, until the contacts 108 are opened by the brush gear.

The sheet-feed mechanism represented by the rectangle 9 19 in FIGURE 2 is described below with reference to FIGURES and 11.

A sheet 110 is shown in contact with the front lays 115 in FIGURE 11. When a sheet is to be fed to the feed device 23 and the cylinder 24 it is gripped by grippers having moving parts 123 and fixed parts 111 and then an arm 121 carrying the fixed and moving parts of the grippers is swung clockwise (considering FIGURES 10 and 11) by turning of a shaft, 122 to which the arm 121 is fixed. The moving parts 123 of the grippers are fixed to an arm 124 which is pivotally connected to the arm 121 and carries cam followers 125 and 125A at its opposite ends. The cam follower 125 engages a cam 126 which is fixed to an arm 130 on which is mounted a cam follower 131 engaging another cam 127. A spring 138 urges the cam 126 to turn anticlockwise about a pivot provided at its upper end. Turning of the cam 127 from its illustrated position results in the cam 126 turning anticlockwise and this results in the arm 124 being turned anticlockwise by a spring (not shown), which causes the grippers to grip the sheet 110, unless this is prevented by the cam follower 125A engaging a cam 128, as it Will be in the illustrated position of that cam. That cam is fixed to a shaft 140 which is normally free to rotateand has fixed to it another arm 141. This arm is pivotally connected to a link 142 which is urged to turn the arm 141 anticlockwise about the axis of the shaft 140 by a spring 143. When the cam 126 tturns anticlockwise as mentioned above, a peg 129 fixed to the cam 126 and projecting into a slot 144 in the link 142 controls the anticlockwise movement of the arm 141 under the action of the spring 143 and this movement of the arm 141 results in similar movement of the shaft 140 and of the cam 128, which moves to a position where it cannot be contacted by the cam follower 125A and prevent the grippers from gripping a sheet. When, however, such prevention is to be effected, the shaft 140 is prevented from rotating and this is done with the aid of an arm 151 (FIGURE 11) fixed on the shaft 140 and cooperating with a pivoted catch 152, which is operated, through links 153, 154 and 155, by solenoids 162 and 164, of which the former has the coil 13 of FIG- URE 1 and the latter has the coil -14 of FIGURE 1. FIG- URE 11 shows the conditions when the coil 13 has been energised and the catch 152 turned clockwise to prevent the shaft 140' from turning. This turning of the catch also prevents the front lays 115 from dropping, by swinging about the axis of a shaft 160, because the catch has a portion 161 which engages a projection 157 fixed to the front lays. The front lays are normally caused to drop by a cam-operated mechanism (not shown) including an arm which is coupled by a spring to an arm 163 which is fixed to the front lays 115. Energisation of the coil 14 of the solenoid 164 causes the catch 152 to turn anticlockwise, thereby releasing the grippers for operation and the front lays for dropping when appropriate.

FIGURE 12 shows a push button 172 which simultaneously closes the switch 11, which is also shown in FIGURE 1, and contacts 173 in a circuit which includes a solenoid coil 175 which operates a clutch (not shown) which starts the sheet separating and feeding-device represented by the number in FIGURE 2. When the first sheet is properly presented to the sheet-feed mechanism represented by the number 19 in FIGURE 1, a contact 174, of one of the disabling relays having the coils 9 and 1-0, is closed and this results in the coil remaining energised even after release of the push button 172.

I claim:

1. A combination of a sheet-fed printing press and an electric control system for controlling it, comprising printing means of the printing press, a sheet-sensing device associated with the press for sensing whether or not a sheet is correctly positioned at a particular location on its way to be printed by the printing means, a pilot relay connected for actuation by the sheet-sensing device, a disabling relay coupled to the printing means for disabling the printing means when it is deenergised, an auxiliary control relay arranged to energise the disabling relay when its own coil is energised and a circuit for energisation of the coil of the auxiliary control relay which comprises three contact arrangements in series, one of the contact arrangements being first and second contact pairs in parallel, the first contact pair being controlled so that it is closed and opened again at predetermined instants in the operating cycle of the printing press and the second contact pair being a holding contact pair which is closed when the coil of the auxiliary control relay is energised, another of the contact arrangements being a contact pair of the pilot relay which is normally closed but in the event of said sheet-sensing device not sensing a correctly positioned sheet during a prescribed period in the operating cycle of the printing press said contact pair of the pilot relay is opened before said first contact pair closes in that cycle and is closed again after said first contact pair opens in that cycle, the third contact arrangement being a normally open contact pair of said disabling relay in parallel with a switch Which is closed by manual operation of means for starting feed of sheets to the press.

2. A combination according to claim 1, wherein the auxiliary control relay releases a sheet-feed mechanism for operation when its coil is energised and stops the sheet-feed mechanism from operating when its coil is deenergised.

3. A combination according to claim 1, wherein there is at least one further disabling relay which has its coil arranged for energisation simultaneously with the coil of the disabling relay that is mentioned in claim 1 and which has a normally open contact in series with the normally open contact that is mentioned in claim 1.

4. A combination according to claim 1, wherein the disabling relay, when de-energised, effects reduction in the speed of the press.

References Cited UNITED STATES PATENTS 3,158,369 11/1'964 Blenner et a1. 1012'47 XR 3,169,476 2/1965 Fielding 101247 3,191,530 6/1965 Fath et a1. 10l--184 FOREIGN PATENTS 901,872 7/1962 Great Britain. 950,771 2/ 1964 Great Britain.

ROBERT L. PULFEY, Primary Examiner.

J. R. FISHER, Assistant Examiner.

US. Cl. X.R 

